1. Field of the Invention
The invention relates to a semiconductor device, particularly, a package type semiconductor device and a method of manufacturing the same.
2. Description of the Related Art
A CSP (chip size package) has received attention in recent years as a new packaging technology. The CSP is a small package having about the same outside dimensions as those of a semiconductor die packaged in it.
A BGA (ball grid array) type semiconductor device has been known as a type of the CSP. The BGA type semiconductor device has a plurality of ball-shaped conductive terminals electrically connected with pad electrodes provided on a semiconductor substrate.
When the BGA type semiconductor device is mounted on electronic equipment, the semiconductor die is electrically connected to an external circuit on a printed board by bonding the conductive terminals to wiring patterns on the printed board.
Such a BGA type semiconductor device has advantages in providing a large number of conductive terminals and in reducing a size over the other CSP type semiconductor devices such as an SOP (small outline package) and a QFP (quad flat Package), which have lead pins protruding from their sides. Therefore, the BGA type semiconductor device has a wide field of application.
FIG. 14 is a schematic cross-sectional view of a conventional BGA type semiconductor device 110. A device element 101 such as a CCD (charge coupled device) image sensor or a CMOS image sensor is formed on the front surface of a semiconductor substrate 100 made of silicon (Si) or the like, and pad electrodes 102 are further formed with a first insulation film 103 interposed therebetween. A glass substrate 104, for example, is further attached on the front surface of the semiconductor substrate 100 with an adhesive layer 105 made of epoxy resin or the like interposed therebetween. Furthermore, a second insulation film 106 made of a silicon oxide film or a silicon nitride film is formed on the side and back surfaces of the semiconductor substrate 100.
Furthermore, wiring layers 107 electrically connected with the pad electrodes 102 are formed on the second insulation film 106. The wiring layers 107 are formed on the side surface and the back surface of the semiconductor substrate 100. A protection layer 108 made of a solder resist or the like is formed covering the second insulation film 106 and the wiring layer 107. Openings are formed in predetermined regions of the protection layer 108 on the wiring layers 107, and ball-shaped conductive terminals 109 are formed being electrically connected with the wiring layers 107 through these openings. The relevant technology is disclosed in Japanese Patent Application Publication No. 2005-072554.
There is a demand for a thinner and smaller device as a whole which includes the above-described package type semiconductor device.
The above-described conventional semiconductor device 110 has a problem that the wiring layer 107 is corroded by a substance causing corrosion such as water, chemicals, metal ion or the like which infiltrates therein in a manufacturing process or in actual use.